Imho they should add to Java the posibility to return more than one value. Now you have a few ways how to do it, but.. you need to write a lot of code to do one simple thing and it is far from being called effective. So why don't have Java for example this posibility:
(int, int, int) xform(int x, int y, int z) ...
(r, g, b) = xform(x, y, z);
(l, a, b) = xform(xform(x, y, z));
It is simple, nice, typesafe..
Btw you can vote for it here ;-)
And second thing - keep primitive types.. Did you ever try to multiply matrix realized as array of immutable double wrappers? It's awfully slow and consumpting big amount of memory..